Overcoming dormancy and light requirements in seeds of Heteropogon contortus, a target species for savanna restoration

As observed at a world scale, in Reunion Island Heteropogon contortus savannas face major pressure and need to be preserved and restored. However, the use of this species in restoration projects is hampered by the limited knowledge about the seed germination ecology and more specifically about dormancy and light requirements. Dormancy state and light requirements for germination of H. contortus seeds were assessed over a 3-year afterripening period (Le. storage). Dormancy loss was observed after one year of storage. Between one and two years of after-ripening, H. contortus seeds exhibit significantly higher mean germination percentages in daily light than in darkness, demonstrating their positive photoblasty (Le. requires light for germination). Smoke solutions significantly enhanced germination in both daily light and darkness during the first two years of dry storage. This study also demonstrated that smoke-infused water with beekeeping smoker fuel could be an efficient method to enhance germination of H. contortus seeds. Overall, this method could be adopted for large scale restoration projects due to its efficiency, its low cost and its reproducibility.